Distonic Dimer Radical Cations of 2,2,6,6-Tetramethylpiperidine as Studied by Optically Detected ESR and Time-Resolved Magnetic Field Effect Techniques

摘要

The question about the liability of aliphatic amine radical cations (RC's) in solutions to react with their parent amine molecules to form dimeric RC's is still under discussion. We obtained using both the OD ESR method and the technique of time-resolved magnetic field effect (TR MFE), that RC's of 2,2,6,6-tetramethylpireridine (TMP) in nonpolar solutions undergo the dimerization to form the distonic dimers N centre dot ..H_2-N~+. In the dimer the unpaired spin density is localized at only one of the nitrogen atoms, whereas the positive charge and the amine proton are displaced towards the second nitrogen atom.